1
|
Mead AJ, Ahluwalia K, Ebright B, Zhang Z, Dave P, Li Z, Zhou E, Naik AA, Ngu R, Chester C, Lu A, Asante I, Pollalis D, Martinez JC, Humayun M, Louie S. Loss of 15-Lipoxygenase in Retinodegenerative RCS Rats. Int J Mol Sci 2024; 25:2309. [PMID: 38396985 PMCID: PMC10889776 DOI: 10.3390/ijms25042309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/08/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
Retinitis pigmentosa (RP) is a retinal degenerative disease associated with a diversity of genetic mutations. In a natural progression study (NPS) evaluating the molecular changes in Royal College of Surgeons (RCS) rats using lipidomic profiling, RNA sequencing, and gene expression analyses, changes associated with retinal degeneration from p21 to p60 were evaluated, where reductions in retinal ALOX15 expression corresponded with disease progression. This important enzyme catalyzes the formation of specialized pro-resolving mediators (SPMs) such as lipoxins (LXs), resolvins (RvDs), and docosapentaenoic acid resolvins (DPA RvDs), where reduced ALOX15 corresponded with reduced SPMs. Retinal DPA RvD2 levels were found to correlate with retinal structural and functional decline. Retinal RNA sequencing comparing p21 with p60 showed an upregulation of microglial inflammatory pathways accompanied by impaired damage-associated molecular pattern (DAMP) clearance pathways. This analysis suggests that ALXR/FPR2 activation can ameliorate disease progression, which was supported by treatment with an LXA4 analog, NAP1051, which was able to promote the upregulation of ALOX12 and ALOX15. This study showed that retinal inflammation from activated microglia and dysregulation of lipid metabolism were central to the pathogenesis of retinal degeneration in RP, where ALXR/FPR2 activation was able to preserve retinal structure and function.
Collapse
Affiliation(s)
- Andrew James Mead
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Kabir Ahluwalia
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Brandon Ebright
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Zeyu Zhang
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Priyal Dave
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Zeyang Li
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Eugene Zhou
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Aditya Anil Naik
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Rachael Ngu
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Catherine Chester
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Angela Lu
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
| | - Isaac Asante
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
- University of Southern California Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA; (D.P.); (J.C.M.); (M.H.)
- University of Southern California Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Dimitrios Pollalis
- University of Southern California Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA; (D.P.); (J.C.M.); (M.H.)
- University of Southern California Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Juan Carlos Martinez
- University of Southern California Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA; (D.P.); (J.C.M.); (M.H.)
- University of Southern California Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Mark Humayun
- University of Southern California Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA; (D.P.); (J.C.M.); (M.H.)
- University of Southern California Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Stan Louie
- Mann School of Pharmacy and Pharmaceutical Sciences, University of Southern California, Los Angeles, CA 90089, USA; (A.J.M.); (K.A.); (B.E.); (Z.Z.); (P.D.); (Z.L.); (E.Z.); (A.A.N.); (R.N.); (C.C.); (A.L.); (I.A.)
- University of Southern California Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA; (D.P.); (J.C.M.); (M.H.)
- University of Southern California Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| |
Collapse
|
2
|
Burnight ER, Wiley LA, Mullin NK, Adur MK, Lang MJ, Cranston CM, Jiao C, Russell SR, Sohn EH, Han IC, Ross JW, Stone EM, Mullins RF, Tucker BA. CRISPRi-Mediated Treatment of Dominant Rhodopsin-Associated Retinitis Pigmentosa. CRISPR J 2023; 6:502-513. [PMID: 38108516 PMCID: PMC11304754 DOI: 10.1089/crispr.2023.0039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 10/30/2023] [Indexed: 12/19/2023] Open
Abstract
Rhodopsin (RHO) mutations such as Pro23His are the leading cause of dominantly inherited retinitis pigmentosa in North America. As with other dominant retinal dystrophies, these mutations lead to production of a toxic protein product, and treatment will require knockdown of the mutant allele. The purpose of this study was to develop a CRISPR-Cas9-mediated transcriptional repression strategy using catalytically inactive Staphylococcus aureus Cas9 (dCas9) fused to the Krüppel-associated box (KRAB) transcriptional repressor domain. Using a reporter construct carrying green fluorescent protein (GFP) cloned downstream of the RHO promoter fragment (nucleotides -1403 to +73), we demonstrate a ∼74-84% reduction in RHO promoter activity in RHOpCRISPRi-treated versus plasmid-only controls. After subretinal transduction of human retinal explants and transgenic Pro23His mutant pigs, significant knockdown of rhodopsin protein was achieved. Suppression of mutant transgene in vivo was associated with a reduction in endoplasmic reticulum (ER) stress and apoptosis markers and preservation of photoreceptor cell layer thickness.
Collapse
Affiliation(s)
- Erin R. Burnight
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Luke A. Wiley
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Nathaniel K. Mullin
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Malavika K. Adur
- Department of Animal Science, Iowa State University, Ames, Iowa, USA
| | - Mallory J. Lang
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Cathryn M. Cranston
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Chunhua Jiao
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Stephen R. Russell
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Elliot H. Sohn
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Ian C. Han
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Jason W. Ross
- Department of Animal Science, Iowa State University, Ames, Iowa, USA
| | - Edwin M. Stone
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Robert F. Mullins
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Budd A. Tucker
- Institute for Vision Research, Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| |
Collapse
|
3
|
Ail D, Nava D, Hwang IP, Brazhnikova E, Nouvel-Jaillard C, Dentel A, Joffrois C, Rousseau L, Dégardin J, Bertin S, Sahel JA, Goureau O, Picaud S, Dalkara D. Inducible nonhuman primate models of retinal degeneration for testing end-stage therapies. SCIENCE ADVANCES 2023; 9:eadg8163. [PMID: 37531424 PMCID: PMC10396314 DOI: 10.1126/sciadv.adg8163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 06/29/2023] [Indexed: 08/04/2023]
Abstract
The anatomical differences between the retinas of humans and most animal models pose a challenge for testing novel therapies. Nonhuman primate (NHP) retina is anatomically closest to the human retina. However, there is a lack of relevant NHP models of retinal degeneration (RD) suitable for preclinical studies. To address this unmet need, we generated three distinct inducible cynomolgus macaque models of RD. We developed two genetically targeted strategies using optogenetics and CRISPR-Cas9 to ablate rods and mimic rod-cone dystrophy. In addition, we created an acute model by physical separation of the photoreceptors and retinal pigment epithelium using a polymer patch. Among the three models, the CRISPR-Cas9-based approach was the most advantageous model in view of recapitulating disease-specific features and its ease of implementation. The acute model, however, resulted in the fastest degeneration, making it the most relevant model for testing end-stage vision restoration therapies such as stem cell transplantation.
Collapse
Affiliation(s)
- Divya Ail
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Diane Nava
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - In Pyo Hwang
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Elena Brazhnikova
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | | | - Alexandre Dentel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, F-75012 Paris, France
- Department of Ophthalmology, Pitié-Salpêtrière University Hospital, F-75013 Paris, France
| | - Corentin Joffrois
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Lionel Rousseau
- ESYCOM, Université Eiffel, CNRS, CNAM, ESIEE Paris, F-77454 Marne-la-Vallée, France
| | - Julie Dégardin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Stephane Bertin
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, F-75012 Paris, France
| | - José-Alain Sahel
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
- CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, F-75012 Paris, France
- Department of Ophthalmology, The University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
- Fondation Ophtalmologique Adolphe de Rothschild, F-75019 Paris, France
| | - Olivier Goureau
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Serge Picaud
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| | - Deniz Dalkara
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, F-75012 Paris, France
| |
Collapse
|
4
|
Bhoi JD, Goel M, Ribelayga CP, Mangel SC. Circadian clock organization in the retina: From clock components to rod and cone pathways and visual function. Prog Retin Eye Res 2023; 94:101119. [PMID: 36503722 PMCID: PMC10164718 DOI: 10.1016/j.preteyeres.2022.101119] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 08/22/2022] [Accepted: 08/25/2022] [Indexed: 12/13/2022]
Abstract
Circadian (24-h) clocks are cell-autonomous biological oscillators that orchestrate many aspects of our physiology on a daily basis. Numerous circadian rhythms in mammalian and non-mammalian retinas have been observed and the presence of an endogenous circadian clock has been demonstrated. However, how the clock and associated rhythms assemble into pathways that support and control retina function remains largely unknown. Our goal here is to review the current status of our knowledge and evaluate recent advances. We describe many previously-observed retinal rhythms, including circadian rhythms of morphology, biochemistry, physiology, and gene expression. We evaluate evidence concerning the location and molecular machinery of the retinal circadian clock, as well as consider findings that suggest the presence of multiple clocks. Our primary focus though is to describe in depth circadian rhythms in the light responses of retinal neurons with an emphasis on clock control of rod and cone pathways. We examine evidence that specific biochemical mechanisms produce these daily light response changes. We also discuss evidence for the presence of multiple circadian retinal pathways involving rhythms in neurotransmitter activity, transmitter receptors, metabolism, and pH. We focus on distinct actions of two dopamine receptor systems in the outer retina, a dopamine D4 receptor system that mediates circadian control of rod/cone gap junction coupling and a dopamine D1 receptor system that mediates non-circadian, light/dark adaptive regulation of gap junction coupling between horizontal cells. Finally, we evaluate the role of circadian rhythmicity in retinal degeneration and suggest future directions for the field of retinal circadian biology.
Collapse
Affiliation(s)
- Jacob D Bhoi
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA
| | - Manvi Goel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Christophe P Ribelayga
- Ruiz Department of Ophthalmology and Visual Science, McGovern Medical School, UTHEALTH-The University of Texas Health Science Center at Houston, Houston, TX, USA; Neuroscience Honors Research Program, William Marsh Rice University, Houston, TX, USA.
| | - Stuart C Mangel
- Department of Neuroscience, Wexner Medical Center, College of Medicine, The Ohio State University, Columbus, OH, USA.
| |
Collapse
|
5
|
Ponce-Mora A, Yuste A, Perini-Villanueva G, Miranda M, Bejarano E. Connexins Biology in the Pathophysiology of Retinal Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1415:229-234. [PMID: 37440038 DOI: 10.1007/978-3-031-27681-1_33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Connexins (Cx) are a family of transmembrane proteins that form gap junction intercellular channels that connect neighboring cells. These channels allow the passage of ions and other biomolecules smaller than 1 kDa, thereby synchronizing the cells both electrically and metabolically. Cxs are expressed in all retinal cell types and the diversity of Cx isoforms involved in the assembly of the channels provides a functional syncytium required for visual transduction. In this chapter, we summarize the status of current knowledge regarding Cx biology in retinal tissues and discuss how Cx dysfunction is associated with retinal disease pathophysiology. Although the contribution of Cx deficiency to retinal degeneration is not well understood, recent findings present Cx as a potential therapeutic target. Therefore, we will briefly discuss pharmacological approaches and gene therapies that are being explored to modulate Cx function and fight sight-threatening eye diseases.
Collapse
Affiliation(s)
- Alejandro Ponce-Mora
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain
| | - Andrea Yuste
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain
| | - Giuliana Perini-Villanueva
- Laboratory for Nutrition and Vision Research, USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA
| | - María Miranda
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain
| | - Eloy Bejarano
- School of Health Sciences and Veterinary School, Universidad CEU Cardenal Herrera, CEU Universities, Valencia, Spain.
| |
Collapse
|
6
|
Zebrafish and inherited photoreceptor disease: Models and insights. Prog Retin Eye Res 2022; 91:101096. [PMID: 35811244 DOI: 10.1016/j.preteyeres.2022.101096] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/20/2022] [Accepted: 06/23/2022] [Indexed: 11/21/2022]
Abstract
Photoreceptor dysfunctions and degenerative diseases are significant causes of vision loss in patients, with few effective treatments available. Targeted interventions to prevent or reverse photoreceptor-related vision loss are not possible without a thorough understanding of the underlying mechanism leading to disease, which is exceedingly difficult to accomplish in the human system. Cone diseases are particularly challenging to model, as some popular genetically modifiable model animals are nocturnal with a rod-dominant visual system and cones that have dissimilarities to human cones. As a result, cone diseases, which affect visual acuity, colour perception, and central vision in patients, are generally poorly understood in terms of pathology and mechanism. Zebrafish (Danio rerio) provide the opportunity to model photoreceptor diseases in a diurnal vertebrate with a cone-rich retina which develops many macular degeneration-like pathologies. Zebrafish undergo external development, allowing early-onset retinal diseases to be detected and studied, and many ophthalmic tools are available for zebrafish visual assessment during development and adulthood. There are numerous zebrafish models of photoreceptor disease, spanning the various types of photoreceptor disease (developmental, rod, cone, and mixed photoreceptor diseases) and genetic/molecular cause. In this review, we explore the features of zebrafish that make them uniquely poised to model cone diseases, summarize the established zebrafish models of inherited photoreceptor disease, and discuss how disease in these models compares to the human presentation, where applicable. Further, we highlight the contributions of these zebrafish models to our understanding of photoreceptor biology and disease, and discuss future directions for utilising and investigating these diverse models.
Collapse
|
7
|
Clinical significance of metabolic quantification for retinal nonperfusion in diabetic retinopathy. Sci Rep 2022; 12:9342. [PMID: 35665762 PMCID: PMC9167306 DOI: 10.1038/s41598-022-13439-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 05/05/2022] [Indexed: 11/16/2022] Open
Abstract
Diabetic retinopathy (DR) is characterized by microvascular changes including ischemia. Degradation and metabolic changes of various retinal cells occur during ischemia. Ischemic region containing more cells will lead to greater metabolic impairment. We analyzed the non-perfusion region (NPR) by integrating histologic mapping with ultra-widefield fluorescein angiography (UWF FA) images. We also investigated the correlations of the weighted ischemic index (ISI) considering the regional distribution of retinal cells with cytokines, macular edema (ME), and neovascularization (NV). In this study, 32 patients with treatment-naïve DR and 21 age-matched control participants were included. The difference between the non-weighted and weighted ISI of NPR with leakage was greatest at the posterior region. The weighted ISI of NPR with leakage was correlated with MCP-1, IL-8, IL-6, PlGF, and VEGF-A levels, while the non-weighted ISI of NPR with leakage was correlated with IL-8 and IL-6 levels. The presence of baseline ME or NV in patients with DR was associated with the weighted ISI, with a stronger association when cones and rods were weighted. The weighted ISI reflecting both metabolic activity and cell distribution demonstrated a better correlation with clinical features and was more valuable in NPR with leakage than non-weighted ISI, which previous studies conventionally used.
Collapse
|
8
|
Roberts PA. Inverse Problem Reveals Conditions for Characteristic Retinal Degeneration Patterns in Retinitis Pigmentosa Under the Trophic Factor Hypothesis. Front Aging Neurosci 2022; 14:765966. [PMID: 35585866 PMCID: PMC9108254 DOI: 10.3389/fnagi.2022.765966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 03/21/2022] [Indexed: 12/05/2022] Open
Abstract
Retinitis pigmentosa (RP) is the most common inherited retinal dystrophy with a prevalence of about 1 in 4,000, affecting approximately 1.5 million people worldwide. Patients with RP experience progressive visual field loss as the retina degenerates, destroying light-sensitive photoreceptor cells (rods and cones), with rods affected earlier and more severely than cones. Spatio-temporal patterns of retinal degeneration in human RP have been well characterised; however, the mechanism(s) giving rise to these patterns have not been conclusively determined. One such mechanism, which has received a wealth of experimental support, is described by the trophic factor hypothesis. This hypothesis suggests that rods produce a trophic factor necessary for cone survival; the loss of rods depletes this factor, leading to cone degeneration. In this article, we formulate a partial differential equation mathematical model of RP in one spatial dimension, spanning the region between the retinal centre (fovea) and the retinal edge (ora serrata). Using this model we derive and solve an inverse problem, revealing for the first time experimentally testable conditions under which the trophic factor mechanism will qualitatively recapitulate the spatio-temporal patterns of retinal regeneration observed in human RP.
Collapse
|
9
|
Amamoto R, Wallick GK, Cepko CL. Retinoic acid signaling mediates peripheral cone photoreceptor survival in a mouse model of retina degeneration. eLife 2022; 11:76389. [PMID: 35315776 PMCID: PMC8940176 DOI: 10.7554/elife.76389] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/25/2022] [Indexed: 12/16/2022] Open
Abstract
Retinitis Pigmentosa (RP) is a progressive, debilitating visual disorder caused by mutations in a diverse set of genes. In both humans with RP and mouse models of RP, rod photoreceptor dysfunction leads to loss of night vision, and is followed by secondary cone photoreceptor dysfunction and degeneration, leading to loss of daylight color vision. A strategy to prevent secondary cone death could provide a general RP therapy to preserve daylight color vision regardless of the underlying mutation. In mouse models of RP, cones in the peripheral retina survive long-term, despite complete rod loss. The mechanism for such peripheral cone survival had not been explored. Here, we found that active retinoic acid (RA) signaling in peripheral Muller glia is necessary for the abnormally long survival of these peripheral cones. RA depletion by conditional knockout of RA synthesis enzymes, or overexpression of an RA degradation enzyme, abrogated the extended survival of peripheral cones. Conversely, constitutive activation of RA signaling in the central retina promoted long-term cone survival. These results indicate that RA signaling mediates the prolonged peripheral cone survival in the rd1 mouse model of retinal degeneration, and provide a basis for a generic strategy for cone survival in the many diseases that lead to loss of cone-mediated vision.
Collapse
Affiliation(s)
- Ryoji Amamoto
- Department of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, United States
| | - Grace K Wallick
- Department of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, United States
| | - Constance L Cepko
- Department of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, United States
| |
Collapse
|
10
|
Visual pigment-deficient cones survive and mediate visual signaling despite the lack of outer segments. Proc Natl Acad Sci U S A 2022; 119:2115138119. [PMID: 35197287 PMCID: PMC8892328 DOI: 10.1073/pnas.2115138119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2021] [Indexed: 11/18/2022] Open
Abstract
Rhodopsin and cone opsins are essential for light detection in vertebrate rods and cones, respectively. It is well established that rhodopsin is required for rod phototransduction, outer segment disk morphogenesis, and rod viability. However, the roles of cone opsins are less well understood. In this study, we adopted a loss-of-function approach to investigate the physiological roles of cone opsins in mice. We showed that cones lacking cone opsins do not form normal outer segments due to the lack of disk morphogenesis. Surprisingly, cone opsin-deficient cones survive for at least 12 mo, which is in stark contrast to the rapid rod degeneration observed in rhodopsin-deficient mice, suggesting that cone opsins are dispensable for cone viability. Although the mutant cones do not respond to light directly, they maintain a normal dark current and continue to mediate visual signaling by relaying the rod signal through rod-cone gap junctions. Our work reveals a striking difference between the role of rhodopsin and cone opsins in photoreceptor viability.
Collapse
|
11
|
Brunet AA, Harvey AR, Carvalho LS. Primary and Secondary Cone Cell Death Mechanisms in Inherited Retinal Diseases and Potential Treatment Options. Int J Mol Sci 2022; 23:ijms23020726. [PMID: 35054919 PMCID: PMC8775779 DOI: 10.3390/ijms23020726] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/05/2022] [Accepted: 01/05/2022] [Indexed: 12/13/2022] Open
Abstract
Inherited retinal diseases (IRDs) are a leading cause of blindness. To date, 260 disease-causing genes have been identified, but there is currently a lack of available and effective treatment options. Cone photoreceptors are responsible for daylight vision but are highly susceptible to disease progression, the loss of cone-mediated vision having the highest impact on the quality of life of IRD patients. Cone degeneration can occur either directly via mutations in cone-specific genes (primary cone death), or indirectly via the primary degeneration of rods followed by subsequent degeneration of cones (secondary cone death). How cones degenerate as a result of pathological mutations remains unclear, hindering the development of effective therapies for IRDs. This review aims to highlight similarities and differences between primary and secondary cone cell death in inherited retinal diseases in order to better define cone death mechanisms and further identify potential treatment options.
Collapse
Affiliation(s)
- Alicia A. Brunet
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Lions Eye Institute Ltd., 2 Verdun St, Nedlands, WA 6009, Australia
- Correspondence: ; Tel.: +61-423-359-714
| | - Alan R. Harvey
- School of Human Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Perron Institute for Neurological and Translational Science, 8 Verdun St, Nedlands, WA 6009, Australia
| | - Livia S. Carvalho
- Centre for Ophthalmology and Visual Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia;
- Lions Eye Institute Ltd., 2 Verdun St, Nedlands, WA 6009, Australia
| |
Collapse
|
12
|
Cone photoreceptor dysfunction in retinitis pigmentosa revealed by optoretinography. Proc Natl Acad Sci U S A 2021; 118:2107444118. [PMID: 34795055 PMCID: PMC8617487 DOI: 10.1073/pnas.2107444118] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2021] [Indexed: 12/20/2022] Open
Abstract
Many blinding diseases afflict photoreceptors, specialized cells in the retina that capture and transduce light to initiate vision. Biomarkers that are sensitive to photoreceptor health are crucial for early detection and effective treatment monitoring of these diseases yet remain elusive. Here, we develop an optical biomarker, based on optoretinographic photoreceptor responses to light stimulation, that reflects the degree of dysfunction of individual cone photoreceptors in patients with retinitis pigmentosa (RP), the most common inherited retinal degenerative disease. Our results show that this biomarker may be beneficial for assessing the functionality of remaining retinal cells in RP patients and for assessing efficacy of treatments such as gene therapy and stem cell transplantation for RP and other diseases afflicting photoreceptors. Retinitis pigmentosa (RP) is the most common group of inherited retinal degenerative diseases, whose most debilitating phase is cone photoreceptor death. Perimetric and electroretinographic methods are the gold standards for diagnosing and monitoring RP and assessing cone function. However, these methods lack the spatial resolution and sensitivity to assess disease progression at the level of individual photoreceptor cells, where the disease originates and whose degradation causes vision loss. High-resolution retinal imaging methods permit visualization of human cone cells in vivo but have only recently achieved sufficient sensitivity to observe their function as manifested in the cone optoretinogram. By imaging with phase-sensitive adaptive optics optical coherence tomography, we identify a biomarker in the cone optoretinogram that characterizes individual cone dysfunction by stimulating cone cells with flashes of light and measuring nanometer-scale changes in their outer segments. We find that cone optoretinographic responses decrease with increasing RP severity and that even in areas where cone density appears normal, cones can respond differently than those in controls. Unexpectedly, in the most severely diseased patches examined, we find isolated cones that respond normally. Short-wavelength–sensitive cones are found to be more vulnerable to RP than medium- and long-wavelength–sensitive cones. We find that decreases in cone response and cone outer-segment length arise earlier in RP than changes in cone density but that decreases in response and length are not necessarily correlated within single cones.
Collapse
|
13
|
Roberts PA. Mathematical Models of Retinitis Pigmentosa: The Trophic Factor Hypothesis. J Theor Biol 2021; 534:110938. [PMID: 34687673 DOI: 10.1016/j.jtbi.2021.110938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 10/20/2022]
Abstract
Retinitis pigmentosa (RP) is the term used to denote a group of inherited retinal-degenerative conditions that cause progressive sight loss. Individuals with this condition lose their light-sensitive photoreceptor cells, known as rods and cones, over a period of years to decades; degeneration starting in the retinal periphery, and spreading peripherally and centrally over time. RP is a rod-cone dystrophy, meaning that rod health and function are affected earlier and more severely than that of cones. Rods degenerate due to an underlying mutation, whereas the reasons for cone degeneration are unknown. A number of mechanisms have been proposed to explain secondary cone loss and the spatio-temporal patterns of retinal degeneration in RP. One of the most promising is the trophic factor hypothesis, which suggests that rods produce a factor necessary for cone survival, such that, when rods degenerate, cone degeneration follows. In this paper we formulate and analyse mathematical models of human RP under the trophic factor hypothesis. These models are constructed as systems of reaction-diffusion partial differential equations in one spatial dimension, and are solved and analysed using a combination of numerical and analytical methods. We predict the conditions under which cones will degenerate following the loss of a patch of rods from the retina, the critical trophic factor treatment rate required to prevent cone degeneration following rod loss and the spatio-temporal patterns of cone loss that would result if the trophic factor mechanism alone were responsible for retinal degeneration.
Collapse
Affiliation(s)
- Paul A Roberts
- School of Life Sciences, University of Sussex, John Maynard Smith Building, Brighton BN1 9QG, UK.
| |
Collapse
|
14
|
Szarka G, Balogh M, Tengölics ÁJ, Ganczer A, Völgyi B, Kovács-Öller T. The role of gap junctions in cell death and neuromodulation in the retina. Neural Regen Res 2021; 16:1911-1920. [PMID: 33642359 PMCID: PMC8343308 DOI: 10.4103/1673-5374.308069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/14/2020] [Accepted: 01/11/2021] [Indexed: 12/26/2022] Open
Abstract
Vision altering diseases, such as glaucoma, diabetic retinopathy, age-related macular degeneration, myopia, retinal vascular disease, traumatic brain injuries and others cripple many lives and are projected to continue to cause anguish in the foreseeable future. Gap junctions serve as an emerging target for neuromodulation and possible regeneration as they directly connect healthy and/or diseased cells, thereby playing a crucial role in pathophysiology. Since they are permeable for macromolecules, able to cross the cellular barriers, they show duality in illness as a cause and as a therapeutic target. In this review, we take recent advancements in gap junction neuromodulation (pharmacological blockade, gene therapy, electrical and light stimulation) into account, to show the gap junction's role in neuronal cell death and the possible routes of rescuing neuronal and glial cells in the retina succeeding illness or injury.
Collapse
Affiliation(s)
- Gergely Szarka
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Márton Balogh
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Ádám J. Tengölics
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Alma Ganczer
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
| | - Béla Völgyi
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Department of Experimental Zoology and Neurobiology, University of Pécs, Pécs, Hungary
- Medical School, University of Pécs, Pécs, Hungary
| | - Tamás Kovács-Öller
- János Szentágothai Research Centre, University of Pécs, Pécs, Hungary
- Retinal Electrical Synapses Research Group, National Brain Research Program (NAP 2.0), Hungarian Academy of Sciences, Budapest, Hungary
- Medical School, University of Pécs, Pécs, Hungary
| |
Collapse
|
15
|
Lin B, Youdim MBH. The protective, rescue and therapeutic potential of multi-target iron-chelators for retinitis pigmentosa. Free Radic Biol Med 2021; 174:1-11. [PMID: 34324978 DOI: 10.1016/j.freeradbiomed.2021.07.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 07/15/2021] [Accepted: 07/23/2021] [Indexed: 12/11/2022]
Abstract
Retinitis pigmentosa (RP) is a group of inherited diseases in which mutations result in the initial loss of night vision, followed by complete blindness. There is currently no effective therapeutic option for RP patients. Given the extremely heterogeneous nature of RP, any causative gene-specific therapy would be practical in a small fraction of patients with RP. Non-gene-specific therapeutics that is applicable to the majority of RP patients regardless of causative mutations may have an enormous impact on RP treatment. Several theories including apoptosis, oxidative stress and neuroinflammation have been proposed as possible underlying mechanisms for photoreceptor death in RP. We have designed and synthesized a series of iron-chelating compounds that possess diverse pharmacological properties and can act in a non-gene-specific manner on multiple pathological features ascribed to Alzheimer's disease, Parkinson's disease and RP. In this review, we discuss the multiple effects of several brain-permeable multi target iron-chelating compounds on photoreceptor degeneration in a mouse model of human RP. Specifically, we focus on the anti-apototic, neuroprotective and neurorescue effects of the compound VK28, M30 and VAR10303 on the histologic and functional preservation of photoreceptors in a mouse model of RP. We consider such drugs as potential therapeutic agents for RP patients.
Collapse
Affiliation(s)
- Bin Lin
- School of Optometry, The Hong Kong Polytechnic University, Kowloon, Hong Kong.
| | - Moussa B H Youdim
- Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
| |
Collapse
|
16
|
Baig A, Buckley D, Codina C. Behavioural Adaptation to Hereditary Macular Dystrophy: A Systematic Review on the Effect of Early Onset Central Field Loss on Peripheral Visual Abilities. Br Ir Orthopt J 2021; 17:104-118. [PMID: 34278226 PMCID: PMC8269784 DOI: 10.22599/bioj.177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/25/2021] [Indexed: 11/30/2022] Open
Abstract
Purpose: Hereditary macular dystrophies (HMD) result in early onset central field loss. Evidence for cortical plasticity has been found in HMD, which may enhance peripheral visual abilities to meet the increased demands and reliance on the peripheral field, as has been found in congenitally deaf adults and habitual action video-game players. This is a qualitative synthesis of the literature on the effect of early onset central field loss on peripheral visual abilities. The knowledge gained may help in developing rehabilitative strategies that enable optimisation of remaining peripheral vision. Methods: A systematic search performed on the Web of Science and PubMED databases yielded 728 records published between 1809 to 2020, of which seven case-control studies were eligible for qualitative synthesis. Results: The search highlighted an overall paucity of literature, which lacked validity due to small heterogeneous samples and deficiencies in reporting of methods and population characteristics. A range of peripheral visual abilities at different eccentricities were studied. Superior performance of HMD observers in the peripheral field or similarities between the preferred retinal loci (PRL) and normal fovea were observed in four of seven studies. Findings were often based on studies including a single observer. Further larger rigorous studies are required in this area. Conclusions: Spontaneous perceptual learning through reliance on and repeated use of the peripheral field and PRL may result in some specific superior peripheral visual abilities. However, worse performance in some tasks could reflect unexpected rod disease, lack of intensive training, or persistent limitations due to the need for cones for specific tasks. Perceptual learning through training regimes could enable patients to optimise use of the PRL and remaining peripheral vision. However, further studies are needed to design optimal training regimes.
Collapse
|
17
|
Viegas FO, Neuhauss SCF. A Metabolic Landscape for Maintaining Retina Integrity and Function. Front Mol Neurosci 2021; 14:656000. [PMID: 33935647 PMCID: PMC8081888 DOI: 10.3389/fnmol.2021.656000] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/22/2021] [Indexed: 01/27/2023] Open
Abstract
Neurons have high metabolic demands that are almost exclusively met by glucose supplied from the bloodstream. Glucose is utilized in complex metabolic interactions between neurons and glia cells, described by the astrocyte-neuron lactate shuttle (ANLS) hypothesis. The neural retina faces similar energy demands to the rest of the brain, with additional high anabolic needs to support continuous renewal of photoreceptor outer segments. This demand is met by a fascinating variation of the ANLS in which photoreceptors are the central part of a metabolic landscape, using glucose and supplying surrounding cells with metabolic intermediates. In this review we summarize recent evidence on how neurons, in particular photoreceptors, meet their energy and biosynthetic requirements by comprising a metabolic landscape of interdependent cells.
Collapse
Affiliation(s)
- Filipe O Viegas
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.,Life Science Zurich Graduate School, Ph.D. Program in Molecular Life Sciences, Zurich, Switzerland
| | - Stephan C F Neuhauss
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| |
Collapse
|
18
|
Arsiwalla TA, Cornish EE, Nguyen PV, Korsakova M, Ali H, Saakova N, Fraser CL, Jamieson RV, Grigg JR. Assessing Residual Cone Function in Retinitis Pigmentosa Patients. Transl Vis Sci Technol 2020; 9:29. [PMID: 33364083 PMCID: PMC7746956 DOI: 10.1167/tvst.9.13.29] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/29/2020] [Indexed: 01/08/2023] Open
Abstract
Purpose The purpose of this study was to investigate cone function deterioration in patients with retinitis pigmentosa (RP) using full field electroretinogram (ffERG), pattern electroretinogram (pERG), and optical coherence tomography (OCT) and their correlation with visual acuity (VA). Methods Clinical records (2008–2018) of patients with RP undergoing repeat electrophysiology were reviewed. Results of ffERG (30 Hz flicker and fused flicker amplitude [FFAmp]), pERG [p50 and n95], and macular OCT (ellipsoid zone [EZ] and outer segment thickness) were collected. Results One hundred twenty-six eyes from 63 patients (33 women, mean age 35 years) were included. The mean decline in VA was 0.11 ± 0.14 logarithm of minimum angle of resolution (logMAR). The FFAmp decreased by 3.01 ± 5.9 µV with global cone function deteriorating by 18.7% annually. The percentage change in FFAmp (RE [r = 0.553], LE [r = 0.531]), and 30 Hz flicker amplitude (RE [r = 0.615], LE [r = 0.529]) strongly correlated with VA (P < 0.00001). The pERG p50 (15 and 30 degrees) change analyzed in 34 patients showed reduction by 23% and 23.4%, respectively. The percentage change in p50 30 degrees (r = 0.397) correlated with VA and EZ layer (P < 0.05). The EZ layer change was calculated in 45 patients and the shortening and thinning rate was 4.3% and 4.4% annually, respectively. The EZ length percentage change correlated with VA (RE [r = 0.34] and LE [r = 0.466; P < 0.05). Conclusions We quantified the decline in cone function in patients with RP utilizing ffERG and FFAmp measures of residual cone function. These parameters correlated with VA and OCT when measurable. These objective measures may assist in monitoring disease progression. Translational Relevance Residual cone function provides an objective estimate of residual visual function, which aids in counselling patients regarding prognosis.
Collapse
Affiliation(s)
- Tasneem A Arsiwalla
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Sydney Eye Hospital Foundation, University of Sydney, Sydney, New South Wales, Australia
| | - Elisa E Cornish
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, New South Wales, Australia.,Sydney Eye Hospital Foundation, University of Sydney, Sydney, New South Wales, Australia
| | - Phuc Vuong Nguyen
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Maria Korsakova
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Haipha Ali
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Nonna Saakova
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Clare L Fraser
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Robyn V Jamieson
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, New South Wales, Australia
| | - John R Grigg
- Save Sight Institute, The Discipline of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Eye Genetics Research Unit, Children's Medical Research Institute, The Children's Hospital at Westmead, Save Sight Institute, University of Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
19
|
Newton F, Megaw R. Mechanisms of Photoreceptor Death in Retinitis Pigmentosa. Genes (Basel) 2020; 11:genes11101120. [PMID: 32987769 PMCID: PMC7598671 DOI: 10.3390/genes11101120] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 09/15/2020] [Accepted: 09/22/2020] [Indexed: 02/08/2023] Open
Abstract
Retinitis pigmentosa (RP) is the most common cause of inherited blindness and is characterised by the progressive loss of retinal photoreceptors. However, RP is a highly heterogeneous disease and, while much progress has been made in developing gene replacement and gene editing treatments for RP, it is also necessary to develop treatments that are applicable to all causative mutations. Further understanding of the mechanisms leading to photoreceptor death is essential for the development of these treatments. Recent work has therefore focused on the role of apoptotic and non-apoptotic cell death pathways in RP and the various mechanisms that trigger these pathways in degenerating photoreceptors. In particular, several recent studies have begun to elucidate the role of microglia and innate immune response in the progression of RP. Here, we discuss some of the recent progress in understanding mechanisms of rod and cone photoreceptor death in RP and summarise recent clinical trials targeting these pathways.
Collapse
Affiliation(s)
- Fay Newton
- MRC Human Genetics Unit, University of Edinburgh, South Bridge, Edinburgh EH8 9YL, UK;
- Correspondence:
| | - Roly Megaw
- MRC Human Genetics Unit, University of Edinburgh, South Bridge, Edinburgh EH8 9YL, UK;
- Princess Alexandra Eye Pavilion, NHS Lothian, Edinburgh EH3 9HA, UK
| |
Collapse
|
20
|
Foote KG, Wong JJ, Boehm AE, Bensinger E, Porco TC, Roorda A, Duncan JL. Comparing Cone Structure and Function in RHO- and RPGR-Associated Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2020; 61:42. [PMID: 32343782 PMCID: PMC7401955 DOI: 10.1167/iovs.61.4.42] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Purpose To study cone structure and function in patients with retinitis pigmentosa (RP) owing to mutations in rhodopsin (RHO), expressed in rod outer segments, and mutations in the RP-GTPase regulator (RPGR) gene, expressed in the connecting cilium of rods and cones. Methods Four eyes of 4 patients with RHO mutations, 5 eyes of 5 patients with RPGR mutations, and 4 eyes of 4 normal subjects were studied. Cone structure was studied with confocal and split-detector adaptive optics scanning laser ophthalmoscopy (AOSLO) and spectral-domain optical coherence tomography. Retinal function was measured using a 543-nm AOSLO-mediated adaptive optics microperimetry (AOMP) stimulus. The ratio of sensitivity to cone density was compared between groups using the Wilcoxon rank-sum test. Results AOMP sensitivity/cone density in patients with RPGR mutations was significantly lower than normal (P< 0.001) and lower than patients with RHO mutations (P< 0.015), whereas patients with RHO mutations were similar to normal (P> 0.9). Conclusions Retinal sensitivity/cone density was lower in patients with RPGR mutations than normal and lower than patients with RHO mutations, perhaps because cones express RPGR and degenerate primarily, whereas cones in eyes with RHO mutations die secondary to rod degeneration. High-resolution microperimetry can reveal differences in cone degeneration in patients with different forms of RP.
Collapse
|
21
|
Ikelle L, Al-Ubaidi MR, Naash MI. Pluripotent Stem Cells for the Treatment of Retinal Degeneration: Current Strategies and Future Directions. Front Cell Dev Biol 2020; 8:743. [PMID: 32923439 PMCID: PMC7457054 DOI: 10.3389/fcell.2020.00743] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/16/2020] [Indexed: 01/14/2023] Open
Abstract
Stem cells have been part of the biomedical landscape since the early 1960s. However, the translation of stem cells to effective therapeutics have met significant challenges, especially for retinal diseases. The retina is a delicate and complex architecture of interconnected cells that are steadfastly interdependent. Degenerative mechanisms caused by acquired or inherited diseases disrupt this interconnectivity, devastating the retina and causing severe vision loss in many patients. Consequently, retinal differentiation of exogenous and endogenous stem cells is currently being explored as replacement therapies in the debilitating diseases. In this review, we will examine the mechanisms involved in exogenous stem cells differentiation and the challenges of effective integration to the host retina. Furthermore, we will explore the current advancements in trans-differentiation of endogenous stem cells, primarily Müller glia.
Collapse
Affiliation(s)
- Larissa Ikelle
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muayyad R Al-Ubaidi
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| | - Muna I Naash
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States
| |
Collapse
|
22
|
Rod function deficit in retained photoreceptors of patients with class B Rhodopsin mutations. Sci Rep 2020; 10:12552. [PMID: 32724127 PMCID: PMC7387454 DOI: 10.1038/s41598-020-69456-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/09/2020] [Indexed: 12/27/2022] Open
Abstract
A common inherited retinal disease is caused by mutations in RHO expressed in rod photoreceptors that provide vision in dim ambient light. Approximately half of all RHO mutations result in a Class B phenotype where mutant rods are retained in some retinal regions but show severe degeneration in other regions. We determined the natural history of dysfunction and degeneration of retained rods by serially evaluating patients. Even when followed for more than 20 years, rod function and structure at some retinal locations could remain unchanged. Other locations showed loss of both vision and photoreceptors but the rate of rod vision loss was greater than the rate of photoreceptor degeneration. This unexpected divergence in rates with disease progression implied the development of a rod function deficit beyond loss of cells. The divergence of progression rates was also detectable over a short interval of 2 years near the health-disease transition in the superior retina. A model of structure–function relationship supported the existence of a large rod function deficit which was also most prominent near regions of health-disease transition. Our studies support the realistic therapeutic goal of improved night vision for retinal regions specifically preselected for rod function deficit in patients.
Collapse
|
23
|
Di Pierdomenico J, Martínez-Vacas A, Hernández-Muñoz D, Gómez-Ramírez AM, Valiente-Soriano FJ, Agudo-Barriuso M, Vidal-Sanz M, Villegas-Pérez MP, García-Ayuso D. Coordinated Intervention of Microglial and Müller Cells in Light-Induced Retinal Degeneration. Invest Ophthalmol Vis Sci 2020; 61:47. [PMID: 32232352 PMCID: PMC7401701 DOI: 10.1167/iovs.61.3.47] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Purpose To analyze the role of microglial and Müller cells in the formation of rings of photoreceptor degeneration caused by phototoxicity. Methods Two-month-old Sprague-Dawley rats were exposed to light and processed 1, 2, or 3 months later. Retinas were dissected as whole-mounts, immunodetected for microglial cells, Müller cells, and S- and L/M-cones and analyzed using fluorescence, thunder imaging, and confocal microscopy. Cone populations were automatically counted and isodensity maps constructed to document cone topography. Results Phototoxicity causes a significant progressive loss of S- and L/M-cones of up to 68% and 44%, respectively, at 3 months after light exposure (ALE). One month ALE, we observed rings of cone degeneration in the photosensitive area of the superior retina. Two and 3 months ALE, these rings had extended to the central and inferior retina. Within the rings of cone degeneration, there were degenerating cones, often activated microglial cells, and numerous radially oriented processes of Müller cells that showed increased expression of intermediate filaments. Between 1 and 3 months ALE, the rings coalesced, and at the same time the microglial cells resumed a mosaic-like distribution, and there was a decrease of Müller cell gliosis at the areas devoid of cones. Conclusions Light-induced photoreceptor degeneration proceeds with rings of cone degeneration, as observed in inherited retinal degenerations in which cone death is secondary to rod degeneration. The spatiotemporal relationship of cone death microglial cell activation and Müller cell gliosis within the rings of cone degeneration suggests that, although both glial cells are involved in the formation of the rings, they may have coordinated actions and, while microglial cells may be more involved in photoreceptor phagocytosis, Müller cells may be more involved in cone and microglial cell migration, retinal remodeling and glial seal formation.
Collapse
|
24
|
Ramachandra Rao S, Skelton LA, Wu F, Onysk A, Spolnik G, Danikiewicz W, Butler MC, Stacks DA, Surmacz L, Mu X, Swiezewska E, Pittler SJ, Fliesler SJ. Retinal Degeneration Caused by Rod-Specific Dhdds Ablation Occurs without Concomitant Inhibition of Protein N-Glycosylation. iScience 2020; 23:101198. [PMID: 32526701 PMCID: PMC7287266 DOI: 10.1016/j.isci.2020.101198] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/10/2020] [Accepted: 05/20/2020] [Indexed: 12/16/2022] Open
Abstract
Dehydrodolichyl diphosphate synthase (DHDDS) catalyzes the committed step in dolichol synthesis. Recessive mutations in DHDDS cause retinitis pigmentosa (RP59), resulting in blindness. We hypothesized that rod photoreceptor-specific ablation of Dhdds would cause retinal degeneration due to diminished dolichol-dependent protein N-glycosylation. Dhddsflx/flx mice were crossed with rod-specific Cre recombinase-expressing (Rho-iCre75) mice to generate rod-specific Dhdds knockout mice (Dhddsflx/flx iCre+). In vivo morphological and electrophysiological evaluation of Dhddsflx/flx iCre+ retinas revealed mild retinal dysfunction at postnatal (PN) 4 weeks, compared with age-matched controls; however, rapid photoreceptor degeneration ensued, resulting in almost complete loss of rods and cones by PN 6 weeks. Retina dolichol levels were markedly decreased by PN 4 weeks in Dhddsflx/flx iCre+ mice, relative to controls; despite this, N-glycosylation of retinal proteins, including opsin (the dominant rod-specific glycoprotein), persisted in Dhddsflx/flx iCre+ mice. These findings challenge the conventional mechanistic view of RP59 as a congenital disorder of glycosylation. Deletion of Dhdds in rod cells caused rapid retinal degeneration in mice Retinal dolichol levels markedly decreased before onset of degeneration Protein N-glycosylation was uncompromised despite Dhdds deletion Degeneration also involved gliosis, microglial activation, and phagoptosis
Collapse
Affiliation(s)
- Sriganesh Ramachandra Rao
- Department of Ophthalmology/Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14209, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY 142015, USA; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA
| | - Lara A Skelton
- Department of Ophthalmology/Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14209, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY 142015, USA; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA
| | - Fuguo Wu
- Department of Ophthalmology/Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14209, USA; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA; New York State Center of Excellence in Bioinformatics and Life Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA
| | - Agnieszka Onysk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Grzegorz Spolnik
- Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw 02106, Poland
| | - Witold Danikiewicz
- Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw 02106, Poland
| | - Mark C Butler
- Department of Ophthalmology/Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14209, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY 142015, USA
| | - Delores A Stacks
- Department of Optometry and Vision Science, Vision Science Research Center, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Liliana Surmacz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Xiuqian Mu
- Department of Ophthalmology/Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14209, USA; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA; New York State Center of Excellence in Bioinformatics and Life Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA
| | - Ewa Swiezewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Steven J Pittler
- Department of Optometry and Vision Science, Vision Science Research Center, School of Optometry, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Steven J Fliesler
- Department of Ophthalmology/Ross Eye Institute, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14209, USA; Research Service, VA Western NY Healthcare System, Buffalo, NY 142015, USA; Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, State University of New York- University at Buffalo, Buffalo, NY 14203, USA.
| |
Collapse
|
25
|
Gorbatyuk MS, Starr CR, Gorbatyuk OS. Endoplasmic reticulum stress: New insights into the pathogenesis and treatment of retinal degenerative diseases. Prog Retin Eye Res 2020; 79:100860. [PMID: 32272207 DOI: 10.1016/j.preteyeres.2020.100860] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 03/08/2020] [Accepted: 03/17/2020] [Indexed: 12/13/2022]
Abstract
Physiological equilibrium in the retina depends on coordinated work between rod and cone photoreceptors and can be compromised by the expression of mutant proteins leading to inherited retinal degeneration (IRD). IRD is a diverse group of retinal dystrophies with multifaceted molecular mechanisms that are not fully understood. In this review, we focus on the contribution of chronically activated unfolded protein response (UPR) to inherited retinal pathogenesis, placing special emphasis on studies employing genetically modified animal models. As constitutively active UPR in degenerating retinas may activate pro-apoptotic programs associated with oxidative stress, pro-inflammatory signaling, dysfunctional autophagy, free cytosolic Ca2+ overload, and altered protein synthesis rate in the retina, we focus on the regulatory mechanisms of translational attenuation and approaches to overcoming translational attenuation in degenerating retinas. We also discuss current research on the role of the UPR mediator PERK and its downstream targets in degenerating retinas and highlight the therapeutic benefits of reprogramming PERK signaling in preclinical animal models of IRD. Finally, we describe pharmacological approaches targeting UPR in ocular diseases and consider their potential applications to IRD.
Collapse
Affiliation(s)
- Marina S Gorbatyuk
- The University of Alabama at Birmingham, Department of Optometry and Vision Science, School of Optometry, USA.
| | - Christopher R Starr
- The University of Alabama at Birmingham, Department of Optometry and Vision Science, School of Optometry, USA
| | - Oleg S Gorbatyuk
- The University of Alabama at Birmingham, Department of Optometry and Vision Science, School of Optometry, USA
| |
Collapse
|
26
|
Ivanova E, Kovacs-Oller T, Sagdullaev BT. Domain-specific distribution of gap junctions defines cellular coupling to establish a vascular relay in the retina. J Comp Neurol 2019; 527:2675-2693. [PMID: 30950036 PMCID: PMC6721971 DOI: 10.1002/cne.24699] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/02/2019] [Accepted: 04/02/2019] [Indexed: 12/22/2022]
Abstract
In the retina, diverse functions of neuronal gap junctions (GJs) have been established. However, the distribution and function of vascular GJs are less clear. Here in the mouse retina whole mounts, we combined structural immunohistochemical analysis and a functional assessment of cellular coupling with a GJ-permeable tracer Neurobiotin to determine distribution patterns of three major vascular connexins. We found that Cx43 was expressed in punctate fashion on astroglia, surrounding all types of blood vessels and in continuous string-like structures along endothelial cell contacts in specialized regions of the vascular tree. Specifically, these Cx43-positive strings originated at the finest capillaries and extended toward the feeding artery. As this structural arrangement promoted strong and exclusive coupling of pericytes and endothelial cells along the corresponding branch, we termed this region a "vascular relay." Cx40 expression was found predominantly along the endothelial cell contacts of the primary arteries and did not overlap with Cx43-positive strings. At their occupied territories, Cx43 and Cx40 clustered with tight junctions and, to a lesser extent, with adhesion contacts, both key elements of the blood-retina barrier. Finally, Cx37 puncta were associated with the entire surface of both mural and endothelial cells across all regions of the vascular tree. This combinatorial analysis of vascular connexins and identification of the vascular relay region will serve as a structural foundation for future studies of neurovascular signaling in health and disease.
Collapse
Affiliation(s)
- Elena Ivanova
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| | - Tamas Kovacs-Oller
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| | - Botir T Sagdullaev
- Burke Neurological Institute, Department of Ophthalmology, Weill Cornell Medicine, White Plains, New York
| |
Collapse
|
27
|
Piano I, D'Antongiovanni V, Testai L, Calderone V, Gargini C. A Nutraceutical Strategy to Slowing Down the Progression of Cone Death in an Animal Model of Retinitis Pigmentosa. Front Neurosci 2019; 13:461. [PMID: 31156364 PMCID: PMC6533548 DOI: 10.3389/fnins.2019.00461] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 04/24/2019] [Indexed: 11/13/2022] Open
Abstract
Retinitis pigmentosa (RP) is an inherited retinal dystrophy characterized by progressive degeneration of the visual cells and abnormalities in retinal pigment epithelium, the vision is lost slowly, and the final outcome is total blindness. RP primarily affects rods, but cones can also be affected as a secondary effect. Photoreceptor cell death is usually triggered by apoptosis, however the molecular mechanisms linking the rod degeneration to the secondary cone death are poorly understood. Possible causes of the secondary cone death are oxidative stress and/ or the release of toxic factors from dying rods. The aim of this study is to analyze the effect of nutraceutical molecules with antioxidant properties, on the progression of the disease in an established animal model of RP, and rd10 mice. We show that chronic treatment per os with a flavanone (naringenin) or a flavonol (quercetin) present in citrus fruits, grapes and apples, preserves retinal morphology, and ameliorates functionality. These actions are associated with a significant reduction of stress-oxidative markers, such as the detoxifying enzymes Sod1 and Sod2. In addition, naringenin and quercetin treatment reduces the levels of acrolein staining associated with a reduction of ROS in the cellular environment. The study demonstrates the beneficial effects of naringenin and quercetin, two molecules that possess antioxidant properties, limiting neurodegeneration, and thus preventing cone damage.
Collapse
Affiliation(s)
- Ilaria Piano
- Department of Pharmacy, University of Pisa, Pisa, Italy
| | | | - Lara Testai
- Department of Pharmacy, University of Pisa, Pisa, Italy
| | | | | |
Collapse
|
28
|
Ivanova E, Alam NM, Prusky GT, Sagdullaev BT. Blood-retina barrier failure and vision loss in neuron-specific degeneration. JCI Insight 2019; 5:126747. [PMID: 30888334 PMCID: PMC6538333 DOI: 10.1172/jci.insight.126747] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 03/14/2019] [Indexed: 12/21/2022] Open
Abstract
Changes in neuronal activity alter blood flow to match energy demand with the supply of oxygen and nutrients. This functional hyperemia is maintained by interactions between neurons, vascular cells, and glia. However, how changing neuronal activity prevalent at the onset of neurodegenerative disease affects neurovascular elements is unclear. Here, in mice with photoreceptor degeneration, a model of neuron-specific dysfunction, we combined assessment of visual function, neurovascular unit structure, and the blood-retina barrier permeability. We found that the rod loss paralleled remodeling of the neurovascular unit, comprised of photoreceptors, retinal pigment epithelium, and Muller glia. When significant visual function was still present, blood flow became disrupted and blood-retina barrier began to fail, facilitating cone loss and vision decline. Thus, in contrast to the established view, vascular deficit in neuronal degeneration is not a late consequence of neuronal dysfunction, but is present early in the course of disease. These findings further establish the importance of vascular deficit and blood retina barrier function in neuron-specific loss, and highlight it as a target for early therapeutic intervention.
Collapse
|
29
|
Di Pierdomenico J, García-Ayuso D, Agudo-Barriuso M, Vidal-Sanz M, Villegas-Pérez MP. Role of microglial cells in photoreceptor degeneration. Neural Regen Res 2019; 14:1186-1190. [PMID: 30804243 PMCID: PMC6425827 DOI: 10.4103/1673-5374.251204] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Inherited photoreceptor degeneration in humans constitutes a major cause of irreversible blindness in the world. They comprise various diseases, but retinitis pigmentosa is the most frequently observed. Retinitis pigmentosa is commonly limited to the eye, where there is progressive photoreceptor degeneration, rods and secondarily cones. The mechanisms of cone and rod degeneration continue to be investigated, since most of the mutations causing retinitis pigmentosa affect rods and thus, the secondary death of cones is an intriguing question but, ultimately, the cause of blindness. Understanding the mechanisms of rod and cone degeneration could help us to develop therapies to stop or, at least, slow down the degeneration process. Secondary cone degeneration has been attributed to the trophic dependence between rods and cones, but microglial cell activation could also have a role. In this review, based on previous work carried out in our laboratory in early stages of photoreceptor degeneration in two animal models of retinitis pigmentosa, we show that microglial cell activation is observed prior to the the initiation of photoreceptor death. We also show that there is an increase of the retinal microglial cell densities and invasion of the outer retinal layers by microglial cells. The inhibition of the microglial cells improves photoreceptor survival and morphology, documenting a role for microglial cells in photoreceptor degeneration. Furthermore, these results indicate that the modulation of microglial cell reactivity can be used to prevent or diminish photoreceptor death in inherited photoreceptor degenerations.
Collapse
Affiliation(s)
- Johnny Di Pierdomenico
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, and Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Diego García-Ayuso
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, and Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Marta Agudo-Barriuso
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, and Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - Manuel Vidal-Sanz
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, and Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| | - María Paz Villegas-Pérez
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia, and Instituto Murciano de Investigación Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Virgen de la Arrixaca), Murcia, Spain
| |
Collapse
|
30
|
Vision Restoration in Outer Retinal Degenerations: Current Approaches and Future Directions. Int Ophthalmol Clin 2018; 59:59-69. [PMID: 30585918 DOI: 10.1097/iio.0000000000000257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
31
|
O'Brien J, Bloomfield SA. Plasticity of Retinal Gap Junctions: Roles in Synaptic Physiology and Disease. Annu Rev Vis Sci 2018; 4:79-100. [DOI: 10.1146/annurev-vision-091517-034133] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Electrical synaptic transmission via gap junctions underlies direct and rapid neuronal communication in the central nervous system. The diversity of functional roles played by electrical synapses is perhaps best exemplified in the vertebrate retina, in which gap junctions are expressed by each of the five major neuronal types. These junctions are highly plastic; they are dynamically regulated by ambient illumination and circadian rhythms acting through light-activated neuromodulators. The networks formed by electrically coupled neurons provide plastic, reconfigurable circuits positioned to play key and diverse roles in the transmission and processing of visual information at every retinal level. Recent work indicates gap junctions also play a role in the progressive cell death and aberrant activity seen in various pathological conditions of the retina. Gap junctions thus form potential targets for novel neuroprotective therapies in the treatment of neurodegenerative retinal diseases such as glaucoma and ischemic retinopathies.
Collapse
Affiliation(s)
- John O'Brien
- Department of Ophthalmology and Visual Science, University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Stewart A. Bloomfield
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, NY 10036, USA
| |
Collapse
|
32
|
Cell Death Pathways in Mutant Rhodopsin Rat Models Identifies Genotype-Specific Targets Controlling Retinal Degeneration. Mol Neurobiol 2018; 56:1637-1652. [PMID: 29911255 DOI: 10.1007/s12035-018-1192-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 06/08/2018] [Indexed: 12/24/2022]
Abstract
Retinitis pigmentosa (RP) is a group of inherited neurological disorders characterized by rod photoreceptor cell death, followed by secondary cone cell death leading to progressive blindness. Currently, there are no viable treatment options for RP. Due to incomplete knowledge of the molecular signaling pathways associated with RP pathogenesis, designing therapeutic strategies remains a challenge. In particular, preventing secondary cone photoreceptor cell loss is a key goal in designing potential therapies. In this study, we identified the main drivers of rod cell death and secondary cone loss in the transgenic S334ter rhodopsin rat model, tested the efficacy of specific cell death inhibitors on retinal function, and compared the effect of combining drugs to target multiple pathways in the S334ter and P23H rhodopsin rat models. The primary driver of early rod cell death in the S334ter model was a caspase-dependent process, whereas cone cell death occurred though RIP3-dependent necroptosis. In comparison, rod cell death in the P23H model was via necroptotic signaling, whereas cone cell loss occurred through inflammasome activation. Combination therapy of four drugs worked better than the individual drugs in the P23H model but not in the S334ter model. These differences imply that treatment modalities need to be tailored for each genotype. Taken together, our data demonstrate that rationally designed genotype-specific drug combinations will be an important requisite to effectively target primary rod cell loss and more importantly secondary cone survival.
Collapse
|
33
|
Ma Y, Han X, de Castro RB, Zhang P, Zhang K, Hu Z, Qin L. Analysis of the bystander effect in cone photoreceptors via a guided neural network platform. SCIENCE ADVANCES 2018; 4:eaas9274. [PMID: 29750200 PMCID: PMC5942910 DOI: 10.1126/sciadv.aas9274] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 03/21/2018] [Indexed: 06/08/2023]
Abstract
The mammalian retina system consists of a complicated photoreceptor structure, which exhibits extensive random synaptic connections. To study retinal development and degeneration, various experimental models have been used previously, but these models are often uncontrollable, are difficult to manipulate, and do not provide sufficient similarity or precision. Therefore, the mechanisms in many retinal diseases remain unclear because of the limited capability in observing the progression and molecular driving forces. For example, photoreceptor degeneration can spread to surrounding healthy photoreceptors via a phenomenon known as the bystander effect; however, no in-depth observations can be made to decipher the molecular mechanisms or the pathways that contribute to the spreading. It is then necessary to build dissociated neural networks to investigate the communications with controllability of cells and their treatment. We developed a neural network chip (NN-Chip) to load single neurons into highly ordered microwells connected by microchannels for synapse formation to build the neural network. By observing the distribution of apoptosis spreading from light-induced apoptotic cones to the surrounding cones, we demonstrated convincing evidence of the existence of a cone-to-cone bystander killing effect. Combining the NN-Chip with microinjection technology, we also found that the gap junction protein connexin 36 (Cx36) is critical for apoptosis spreading and the bystander effect in cones. In addition, our unique NN-Chip platform provides a quantitative, high-throughput tool for investigating signaling mechanisms and behaviors in neurons and opens a new avenue for screening potential drug targets to cure retinal diseases.
Collapse
Affiliation(s)
- Yuan Ma
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- College of Materials Sciences and Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Xin Han
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Ricardo Bessa de Castro
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
- College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Pengchao Zhang
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Kai Zhang
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Zhongbo Hu
- College of Materials Sciences and Optoelectronics, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lidong Qin
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA
- Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
| |
Collapse
|
34
|
A Brief Review on the Pathological Role of Decreased Blood Flow Affected in Retinitis Pigmentosa. J Ophthalmol 2018; 2018:3249064. [PMID: 29682340 PMCID: PMC5845519 DOI: 10.1155/2018/3249064] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/09/2018] [Accepted: 01/23/2018] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa (RP) represents a clinically and genetically heterogeneous disease characterized by progressive photoreceptor loss. In recent years, research has been rarely made in blood flow affected in RP. The specific mechanism of blood flow affected in RP is not completely clear. A number of studies indicated that the decreased blood flow was related to RP. According to clinical observation and treatment experience, Chinese medicine considered that blood stasis runs throughout the RP disease progression, and the blood stasis corresponding to Chinese herbal medicine has a positive effect on the clinical treatment of RP. Therefore, we proposed that the decreased blood flow may participate in the lesion. In this article, we will review the findings on the decreased blood flow affected in RP from the perspective of modern medicine and Chinese medicine.
Collapse
|
35
|
Rajagopal R, Zhang S, Wei X, Doggett T, Adak S, Enright J, Shah V, Ling G, Chen S, Yoshino J, Hsu FF, Semenkovich CF. Retinal de novo lipogenesis coordinates neurotrophic signaling to maintain vision. JCI Insight 2018; 3:97076. [PMID: 29321376 PMCID: PMC5821215 DOI: 10.1172/jci.insight.97076] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Accepted: 11/28/2017] [Indexed: 11/17/2022] Open
Abstract
Membrane lipid composition is central to the highly specialized functions of neurological tissues. In the retina, abnormal lipid metabolism causes severe forms of blindness, often through poorly understood neuronal cell death. Here, we demonstrate that deleting the de novo lipogenic enzyme fatty acid synthase (FAS) from the neural retina, but not the vascular retina, results in progressive neurodegeneration and blindness with a temporal pattern resembling rodent models of retinitis pigmentosa. Blindness was not rescued by protection from light-evoked activity; by eating a diet enriched in palmitate, the product of the FAS reaction; or by treatment with the PPARα agonist fenofibrate. Vision loss was due to aberrant synaptic structure, blunted responsiveness to glial-derived neurotrophic factor and ciliary neurotrophic factor, and eventual apoptotic cell loss. This progressive neurodegeneration was associated with decreased membrane cholesterol content, as well as loss of discrete n-3 polyunsaturated fatty acid- and saturated fatty acid-containing phospholipid species within specialized membrane microdomains. Neurotrophic signaling was restored by exogenous cholesterol delivery. These findings implicate de novo lipogenesis in neurotrophin-dependent cell survival by maintaining retinal membrane configuration and lipid composition, and they suggest that ongoing lipogenesis may be required to prevent cell death in many forms of retinopathy.
Collapse
Affiliation(s)
| | - Sheng Zhang
- Department of Ophthalmology and Visual Sciences
| | - Xiaochao Wei
- Division of Endocrinology, Metabolism, and Lipid Research
| | | | - Sangeeta Adak
- Division of Endocrinology, Metabolism, and Lipid Research
| | | | - Vaishali Shah
- Division of Endocrinology, Metabolism, and Lipid Research
| | - Guoyu Ling
- Division of Endocrinology, Metabolism, and Lipid Research
| | | | - Jun Yoshino
- Division of Geriatrics and Nutritional Science, and
| | - Fong-Fu Hsu
- Division of Endocrinology, Metabolism, and Lipid Research
| | - Clay F Semenkovich
- Division of Endocrinology, Metabolism, and Lipid Research.,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
| |
Collapse
|
36
|
Campochiaro PA, Mir TA. The mechanism of cone cell death in Retinitis Pigmentosa. Prog Retin Eye Res 2017; 62:24-37. [PMID: 28962928 DOI: 10.1016/j.preteyeres.2017.08.004] [Citation(s) in RCA: 177] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2017] [Revised: 08/31/2017] [Accepted: 08/31/2017] [Indexed: 12/16/2022]
Abstract
Retinitis Pigmentosa (RP) is a group of diseases in which one of a large number of mutations causes death of rod photoreceptors. After rods die, cone photoreceptors slowly degenerate in a characteristic pattern. The mechanism of rod cell death varies depending upon the gene that is mutated and the rate that rods degenerate is an important prognostic feature, because cones do not begin to degenerate until almost all rods have been eliminated. Rod cell death causes night blindness, but visual disability and blindness result from cone degeneration and therefore it is critical to determine the mechanisms by which it occurs. The death of rods reduces oxygen consumption resulting in high tissue levels of oxygen in the outer retina. The excess oxygen stimulates superoxide radical production by mismatches in the electron transport chain in mitochondria and by stimulation of NADPH oxidase activity in cytoplasm. The high levels of superoxide radicals overwhelm the antioxidant defense system and generate more reactive species including peroxynitrite which is extremely damaging and difficult to detoxify. This results in progressive oxidative damage in cones which contributes to cone cell death and loss of function because drugs or gene transfer that reduce oxidative stress promote cone survival and maintenance of function. Compared with aqueous humor samples from control patients, those from patients with RP show significant elevation of carbonyl content on proteins indicating oxidative damage and a reduction in the ratio of reduced to oxidized glutathione indicating depletion of a major component of the antioxidant defense system from ongoing oxidative stress. The first step in clinical trials will be to identify doses of therapeutic agents that reverse these biomarkers of disease to assist in design of much longer trials with functional and anatomic endpoints.
Collapse
Affiliation(s)
- Peter A Campochiaro
- Departments of Ophthalmology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
| | - Tahreem A Mir
- Departments of Ophthalmology and Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| |
Collapse
|
37
|
Roberts PA, Gaffney EA, Luthert PJ, Foss AJ, Byrne HM. Mathematical models of retinitis pigmentosa: The oxygen toxicity hypothesis. J Theor Biol 2017; 425:53-71. [DOI: 10.1016/j.jtbi.2017.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 04/29/2017] [Accepted: 05/03/2017] [Indexed: 01/31/2023]
|
38
|
Akopian A, Kumar S, Ramakrishnan H, Roy K, Viswanathan S, Bloomfield SA. Targeting neuronal gap junctions in mouse retina offers neuroprotection in glaucoma. J Clin Invest 2017; 127:2647-2661. [PMID: 28604388 PMCID: PMC5490768 DOI: 10.1172/jci91948] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 04/27/2017] [Indexed: 01/26/2023] Open
Abstract
The progressive death of retinal ganglion cells and resulting visual deficits are hallmarks of glaucoma, but the underlying mechanisms remain unclear. In many neurodegenerative diseases, cell death induced by primary insult is followed by a wave of secondary loss. Gap junctions (GJs), intercellular channels composed of subunit connexins, can play a major role in secondary cell death by forming conduits through which toxic molecules from dying cells pass to and injure coupled neighbors. Here we have shown that pharmacological blockade of GJs or genetic ablation of connexin 36 (Cx36) subunits, which are highly expressed by retinal neurons, markedly reduced loss of neurons and optic nerve axons in a mouse model of glaucoma. Further, functional parameters that are negatively affected in glaucoma, including the electroretinogram, visual evoked potential, visual spatial acuity, and contrast sensitivity, were maintained at control levels when Cx36 was ablated. Neuronal GJs may thus represent potential therapeutic targets to prevent the progressive neurodegeneration and visual impairment associated with glaucoma.
Collapse
|
39
|
Sudharsan R, Simone KM, Anderson NP, Aguirre GD, Beltran WA. Acute and Protracted Cell Death in Light-Induced Retinal Degeneration in the Canine Model of Rhodopsin Autosomal Dominant Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2017; 58:270-281. [PMID: 28114588 PMCID: PMC5464465 DOI: 10.1167/iovs.16-20749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Purpose To characterize a light damage paradigm and establish structural and immunocytochemical measures of acute and protracted light-induced retinal degeneration in the rhodopsin (RHO) T4R dog model of RHO-autosomal dominant retinitis pigmentosa (ADRP). Methods Retinal light damage was induced in mutant dogs with a 1-minute exposure to various light intensities (0.1-1.0 mW/cm2) delivered with a Ganzfeld stimulator, or by fundus photography. Photoreceptor cell death was assessed by TUNEL assay, and alterations in retinal layers were examined by histology and immunohistochemistry 24 hours and 2 weeks after light exposure. Detailed topographic maps were made to document changes in the outer retinal layers of all four retinal quadrants 2 weeks post exposure. Results Twenty-four hours post light exposure, the severity of photoreceptor cell death was dose dependent. Immunohistochemical analysis revealed disruption of rod outer segments, focal loss of the RPE integrity, and an increase in expression of endothelin receptor B in Müller cells with the two highest doses of light and fundus photography. Two weeks after light exposure, persistence of photoreceptor death, thinning of the outer nuclear layer, and induction of Müller cell gliosis occurred with the highest doses of light. Conclusions We have characterized outcome measures of acute and continuing retinal degeneration in the RHO T4R dog following light exposure. These will be used to assess the molecular mechanisms of light-induced damage and rescue strategies in this large animal model of RHO-ADRP.
Collapse
Affiliation(s)
- Raghavi Sudharsan
- Section of Ophthalmology, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Kristina M Simone
- Section of Ophthalmology, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Nathan P Anderson
- Section of Ophthalmology, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Gustavo D Aguirre
- Section of Ophthalmology, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - William A Beltran
- Section of Ophthalmology, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| |
Collapse
|
40
|
Zhu ZH, Fu Y, Weng CH, Zhao CJ, Yin ZQ. Proteomic profiling of early degenerative retina of RCS rats. Int J Ophthalmol 2017; 10:878-889. [PMID: 28730077 DOI: 10.18240/ijo.2017.06.08] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 04/06/2017] [Indexed: 11/23/2022] Open
Abstract
AIM To identify the underlying cellular and molecular changes in retinitis pigmentosa (RP). METHODS Label-free quantification-based proteomics analysis, with its advantages of being more economic and consisting of simpler procedures, has been used with increasing frequency in modern biological research. Dystrophic RCS rats, the first laboratory animal model for the study of RP, possess a similar pathological course as human beings with the diseases. Thus, we employed a comparative proteomics analysis approach for in-depth proteome profiling of retinas from dystrophic RCS rats and non-dystrophic congenic controls through Linear Trap Quadrupole - orbitrap MS/MS, to identify the significant differentially expressed proteins (DEPs). Bioinformatics analyses, including Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway annotation and upstream regulatory analysis, were then performed on these retina proteins. Finally, a Western blotting experiment was carried out to verify the difference in the abundance of transcript factor E2F1. RESULTS In this study, we identified a total of 2375 protein groups from the retinal protein samples of RCS rats and non-dystrophic congenic controls. Four hundred thirty-four significantly DEPs were selected by Student's t-test. Based on the results of the bioinformatics analysis, we identified mitochondrial dysfunction and transcription factor E2F1 as the key initiation factors in early retinal degenerative process. CONCLUSION We showed that the mitochondrial dysfunction and the transcription factor E2F1 substantially contribute to the disease etiology of RP. The results provide a new potential therapeutic approach for this retinal degenerative disease.
Collapse
Affiliation(s)
- Zhi-Hong Zhu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing 400038, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing 400038, China
| | - Yan Fu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing 400038, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing 400038, China
| | - Chuan-Huang Weng
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing 400038, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing 400038, China
| | - Cong-Jian Zhao
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing 400038, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing 400038, China
| | - Zheng-Qin Yin
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical University, Chongqing 400038, China.,Key Lab of Visual Damage and Regeneration & Restoration of Chongqing, Chongqing 400038, China
| |
Collapse
|
41
|
Hou B, Fu Y, Weng C, Liu W, Zhao C, Yin ZQ. Homeostatic Plasticity Mediated by Rod-Cone Gap Junction Coupling in Retinal Degenerative Dystrophic RCS Rats. Front Cell Neurosci 2017; 11:98. [PMID: 28473754 PMCID: PMC5397418 DOI: 10.3389/fncel.2017.00098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/22/2017] [Indexed: 11/14/2022] Open
Abstract
Rod-cone gap junctions open at night to allow rod signals to pass to cones and activate the cone-bipolar pathway. This enhances the ability to detect large, dim objects at night. This electrical synaptic switch is governed by the circadian clock and represents a novel form of homeostatic plasticity that regulates retinal excitability according to network activity. We used tracer labeling and ERG recording in the retinae of control and retinal degenerative dystrophic RCS rats. We found that in the control animals, rod-cone gap junction coupling was regulated by the circadian clock via the modulation of the phosphorylation of the melatonin synthetic enzyme arylalkylamine N-acetyltransferase (AANAT). However, in dystrophic RCS rats, AANAT was constitutively phosphorylated, causing rod-cone gap junctions to remain open. A further b/a-wave ratio analysis revealed that dystrophic RCS rats had stronger synaptic strength between photoreceptors and bipolar cells, possibly because rod-cone gap junctions remained open. This was despite the fact that a decrease was observed in the amplitude of both a- and b-waves as a result of the progressive loss of rods during early degenerative stages. These results suggest that electric synaptic strength is increased during the day to allow cone signals to pass to the remaining rods and to be propagated to rod bipolar cells, thereby partially compensating for the weak visual input caused by the loss of rods.
Collapse
Affiliation(s)
- Baoke Hou
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Department of Ophthalmology, Chinese PLA General HospitalBeijing, China
| | - Yan Fu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Chuanhuang Weng
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Weiping Liu
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Congjian Zhao
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| | - Zheng Qin Yin
- Southwest Hospital/Southwest Eye Hospital, Third Military Medical UniversityChongqing, China.,Key Lab of Visual Damage and Regeneration and Restoration of ChongqingChongqing, China
| |
Collapse
|
42
|
Iribarne M, Nishiwaki Y, Nakamura S, Araragi M, Oguri E, Masai I. Aipl1 is required for cone photoreceptor function and survival through the stability of Pde6c and Gc3 in zebrafish. Sci Rep 2017; 7:45962. [PMID: 28378769 PMCID: PMC5381001 DOI: 10.1038/srep45962] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 03/07/2017] [Indexed: 12/18/2022] Open
Abstract
Genetic mutations in aryl hydrocarbon receptor interacting protein-like 1 (AIPL1) cause photoreceptor degeneration associated with Leber congenital amaurosis 4 (LCA4) in human patients. Here we report retinal phenotypes of a zebrafish aipl1 mutant, gold rush (gosh). In zebrafish, there are two aipl1 genes, aipl1a and aipl1b, which are expressed mainly in rods and cones, respectively. The gosh mutant gene encodes cone-specific aipl1, aipl1b. Cone photoreceptors undergo progressive degeneration in the gosh mutant, indicating that aipl1b is required for cone survival. Furthermore, the cone-specific subunit of cGMP phosphodiesterase 6 (Pde6c) is markedly decreased in the gosh mutant, and the gosh mutation genetically interacts with zebrafish pde6c mutation eclipse (els). These data suggest that Aipl1 is required for Pde6c stability and function. In addition to Pde6c, we found that zebrafish cone-specific guanylate cyclase, zGc3, is also decreased in the gosh and els mutants. Furthermore, zGc3 knockdown embryos showed a marked reduction in Pde6c. These observations illustrate the interdependence of cGMP metabolism regulators between Aipl1, Pde6c, and Gc3 in photoreceptors.
Collapse
Affiliation(s)
- Maria Iribarne
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Yuko Nishiwaki
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Shohei Nakamura
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Masato Araragi
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Eri Oguri
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| | - Ichiro Masai
- Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna, Okinawa, 904-0495, Japan
| |
Collapse
|
43
|
Identification of novel X-linked gain-of-function RPGR-ORF15 mutation in Italian family with retinitis pigmentosa and pathologic myopia. Sci Rep 2016; 6:39179. [PMID: 27995965 PMCID: PMC5171904 DOI: 10.1038/srep39179] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/18/2016] [Indexed: 11/09/2022] Open
Abstract
The aim of this study was to describe a new pathogenic variant in the mutational hot spot exon ORF15 of retinitis pigmentosa GTPase regulator (RPGR) gene within an Italian family with X-linked retinitis pigmentosa (RP), detailing its distinctive genotype-phenotype correlation with pathologic myopia (PM). All members of this RP-PM family underwent a complete ophthalmic examination. The entire open reading frames of RPGR and retinitis pigmentosa 2 genes were analyzed by Sanger sequencing. A novel frame-shift mutation in exon ORF15 of RPGR gene (c.2091_2092insA; p.A697fs) was identified as hemizygous variant in the male proband with RP, and as heterozygous variant in the females of this pedigree who invariably exhibited symmetrical PM in both eyes. The c.2091_2092insA mutation coherently co-segregated with the observed phenotypes. These findings expand the spectrum of X-linked RP variants. Interestingly, focusing on Caucasian ethnicity, just three RPGR mutations are hitherto reported in RP-PM families: one of these is located in exon ORF15, but none appears to be characterized by a high penetrance of PM trait as observed in the present, relatively small, pedigree. The geno-phenotypic attributes of this heterozygosity suggest that gain-of-function mechanism could give rise to PM via a degenerative cell-cell remodeling of the retinal structures.
Collapse
|
44
|
Narayan DS, Wood JPM, Chidlow G, Casson RJ. A review of the mechanisms of cone degeneration in retinitis pigmentosa. Acta Ophthalmol 2016; 94:748-754. [PMID: 27350263 DOI: 10.1111/aos.13141] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/30/2016] [Indexed: 12/12/2022]
Abstract
Retinitis pigmentosa (RP) is an inherited condition that features degeneration of rod and cone photoreceptors. In all forms of RP, the genetic mutation is expressed exclusively in rods; however, cones die too. The secondary death of cones in RP remains somewhat mysterious. A better understanding of the mechanisms that cause cone degeneration in RP could lead to novel treatments that preserve cones. There are a number of prevailing theories that attempt to explain cone degeneration in RP. One concept is that cone survival is dependent on trophic factors produced by rods. Another hypothesis is that cones suffer from a nutrient shortage after rods have been lost. Additionally, oxidative stress and pro-inflammatory microglial activation have also been suggested to play a role in cone death. The present review evaluates the evidence supporting these theories and provides an update on the mechanisms of cone degeneration in RP.
Collapse
Affiliation(s)
- Daniel S. Narayan
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| | - John P. M. Wood
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| | - Glyn Chidlow
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| | - Robert J. Casson
- Ophthalmic Research Laboratories; Hanson Institute Centre for Neurological Diseases; Adelaide South Australia Australia
- South Australian Institute of Ophthalmology; University of Adelaide; Adelaide South Australia Australia
| |
Collapse
|
45
|
Shin JA, Kim HS, Vargas A, Yu WQ, Eom YS, Craft CM, Lee EJ. Inhibition of Matrix Metalloproteinase 9 Enhances Rod Survival in the S334ter-line3 Retinitis Pigmentosa Model. PLoS One 2016; 11:e0167102. [PMID: 27893855 PMCID: PMC5125676 DOI: 10.1371/journal.pone.0167102] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/08/2016] [Indexed: 12/31/2022] Open
Abstract
Retinitis Pigmentosa (RP) is one of the most common forms of inherited visual loss with the initial degeneration of rod photoreceptors, followed by a progressive cone photoreceptor deterioration. Coinciding with this visual loss, the extracellular matrix (ECM) is reorganized, which alters matrix metalloproteinase (MMP) activity levels. A potential pathological role of MMPs, MMP-9 in particular, involves an excitotoxicity-mediated physiological response. In the current study, we examine the MMP-9 and MMP-2 expression levels in the rhodopsin S334ter-line3 RP rat model and investigate the impact of treatment with SB-3CT, a specific MMP-9 and MMP-2 inhibitor, on rod cell survival was tested. Retinal MMP-9 and MMP-2 expression levels were quantified by immunoblot analysis from S334ter-line3 rats compared to controls. Gelatinolytic activities of MMP-9 and MMP-2 by zymography were examined. The geometry of rod death was further evaluated using Voronoi analysis. Our results revealed that MMP-9 was elevated while MMP-2 was relatively unchanged when S334ter-line 3 retinas were compared to controls. With SB-3CT treatment, we observed gelatinolytic activity of both MMPs was decreased and diminished clustering associated with rod death, in addition to a robust preservation of rod photoreceptors. These results demonstrate that up-regulation of MMP-9 in retinas of S334ter-line3 are associated with rod death. The application of SB-3CT dramatically interferes with mechanisms leading to apoptosis in an MMP-9-dependent manner. Future studies will determine the feasibility of using SB-3CT as a potential therapeutic strategy to slow progression of vision loss in genetic inherited forms of human RP.
Collapse
Affiliation(s)
- Jung-A Shin
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
- Department of Anatomy, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Hwa Sun Kim
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
| | - Andrew Vargas
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
| | - Wan-Qing Yu
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
- Department of Biological Structure, University of Washington, Seattle, Washington, United States of America
| | - Yun Sung Eom
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
| | - Cheryl Mae Craft
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
- Department of Cell & Neurobiology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
- Neuroscience Graduate Program, University of Southern California, Los Angeles, California, United States of America
| | - Eun-Jin Lee
- Mary D. Allen Laboratory for Vision Research, USC Roski Eye Institute, Department of Ophthalmology, Keck School of Medicine of the University of Southern California, Los Angeles, California, United States of America
- Department of Biomedical Engineering, University of Southern California Viterbi School of Engineering, Los Angeles, California, United States of America
- * E-mail:
| |
Collapse
|
46
|
Akopian A, Kumar S, Ramakrishnan H, Viswanathan S, Bloomfield SA. Amacrine cells coupled to ganglion cells via gap junctions are highly vulnerable in glaucomatous mouse retinas. J Comp Neurol 2016; 527:159-173. [PMID: 27411041 DOI: 10.1002/cne.24074] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/06/2016] [Accepted: 07/08/2016] [Indexed: 12/22/2022]
Abstract
We determined whether the structural and functional integrity of amacrine cells (ACs), the largest cohort of neurons in the mammalian retina, are affected in glaucoma. Intraocular injection of microbeads was made in mouse eyes to elevate intraocular pressure as a model of experimental glaucoma. Specific immunocytochemical markers were used to identify AC and displaced (d)ACs subpopulations in both the inner nuclear and ganglion cell layers, respectively, and to distinguish them from retinal ganglion cells (RGCs). Calretinin- and γ-aminobutyric acid (GABA)-immunoreactive (IR) cells were highly vulnerable to glaucomatous damage, whereas choline acetyltransferase (ChAT)-positive and glycinergic AC subtypes were unaffected. The AC loss began 4 weeks after initial microbead injection, corresponding to the time course of RGC loss. Recordings of electroretinogram (ERG) oscillatory potentials and scotopic threshold responses, which reflect AC and RGC activity, were significantly attenuated in glaucomatous eyes following a time course that matched that of the AC and RGC loss. Moreover, we found that it was the ACs coupled to RGCs via gap junctions that were lost in glaucoma, whereas uncoupled ACs were largely unaffected. Our results suggest that AC loss in glaucoma occurs secondary to RGC death through the gap junction-mediated bystander effect. J. Comp. Neurol. 527:159-173, 2019. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Abram Akopian
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| | - Sandeep Kumar
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| | | | - Suresh Viswanathan
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| | - Stewart A Bloomfield
- Department of Biological and Vision Sciences, State University of New York College of Optometry, New York, New York, 10036
| |
Collapse
|
47
|
Direct Evidence for Daily Plasticity of Electrical Coupling between Rod Photoreceptors in the Mammalian Retina. J Neurosci 2016; 36:178-84. [PMID: 26740659 DOI: 10.1523/jneurosci.3301-15.2016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED Rod photoreceptors are electrically coupled through gap junctions. Coupling is a key determinant of their light response properties, but whether rod electrical coupling is dynamically regulated remains elusive and controversial. Here, we have obtained direct measurements of the conductance between adjacent rods in mouse retina and present evidence that rod electrical coupling strength is dependent on the time of day, the lighting conditions, and the mouse strain. Specifically, we show in CBA/Ca mice that under circadian conditions, the rod junctional conductance has a median value of 98 pS during the subjective day and of 493 pS during the subjective night. In C57BL/6 mice, the median junctional conductance between dark-adapted rods is ∼140 pS, regardless of the time in the circadian cycle. Adaptation to bright light decreases the rod junctional conductance to ∼0 pS, regardless of the time of day or the mouse strain. Together, these results establish the high degree of plasticity of rod electrical coupling over the course of the day. Estimates of the rod coupling strength will provide a foundation for further investigations of rod interactions and the role of rod coupling in the ability of the visual system to anticipate, assimilate, and respond to the daily changes in ambient light intensity. SIGNIFICANCE STATEMENT Many cells in the CNS communicate via gap junctions, or electrical synapses, the regulation of which remains largely unknown. Here, we show that the strength of electrical coupling between rod photoreceptors of the retina is regulated by the time of day and the lighting conditions. This mechanism may help us understand some key aspects of day and night vision as well as some visual malfunctions.
Collapse
|
48
|
Mathematical and computational models of the retina in health, development and disease. Prog Retin Eye Res 2016; 53:48-69. [PMID: 27063291 DOI: 10.1016/j.preteyeres.2016.04.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 04/05/2016] [Accepted: 04/05/2016] [Indexed: 12/12/2022]
Abstract
The retina confers upon us the gift of vision, enabling us to perceive the world in a manner unparalleled by any other tissue. Experimental and clinical studies have provided great insight into the physiology and biochemistry of the retina; however, there are questions which cannot be answered using these methods alone. Mathematical and computational techniques can provide complementary insight into this inherently complex and nonlinear system. They allow us to characterise and predict the behaviour of the retina, as well as to test hypotheses which are experimentally intractable. In this review, we survey some of the key theoretical models of the retina in the healthy, developmental and diseased states. The main insights derived from each of these modelling studies are highlighted, as are model predictions which have yet to be tested, and data which need to be gathered to inform future modelling work. Possible directions for future research are also discussed. Whilst the present modelling studies have achieved great success in unravelling the workings of the retina, they have yet to achieve their full potential. For this to happen, greater involvement with the modelling community is required, and stronger collaborations forged between experimentalists, clinicians and theoreticians. It is hoped that, in addition to bringing the fruits of current modelling studies to the attention of the ophthalmological community, this review will encourage many such future collaborations.
Collapse
|
49
|
A Naturally-Derived Compound Schisandrin B Enhanced Light Sensation in the pde6c Zebrafish Model of Retinal Degeneration. PLoS One 2016; 11:e0149663. [PMID: 26930483 PMCID: PMC4773124 DOI: 10.1371/journal.pone.0149663] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 02/03/2016] [Indexed: 11/19/2022] Open
Abstract
Retinal degeneration is often progressive. This feature has provided a therapeutic window for intervention that may extend functional vision in patients. Even though this approach is feasible, few promising drug candidates are available. The scarcity of new drugs has motivated research to discover novel compounds through different sources. One such example is Schisandrin B (SchB), an active component isolated from the five-flavor fruit (Fructus Schisandrae) that is postulated in traditional Chinese medicines to exert prophylactic visual benefit. This SchB benefit was investigated in this study in pde6cw59, a zebrafish retinal-degeneration model. In this model, the pde6c gene (phosphodiesterase 6C, cGMP-specific, cone, alpha prime) carried a mutation which caused cone degeneration. This altered the local environment and caused the bystander rods to degenerate too. To test SchB on the pde6cw59 mutants, a treatment concentration was first determined that would not cause morphological defects, and would initiate known physiological response. Then, the mutants were treated with the optimized SchB concentration before the appearance of retinal degeneration at 3 days postfertilization (dpf). The light sensation of animals was evaluated at 6 dpf by the visual motor response (VMR), a visual startle that could be initiated by drastic light onset and offset. The results show that the VMR of pde6cw59 mutants towards light onset was enhanced by the SchB treatment, and that the initial phase of the enhancement was primarily mediated through the mutants’ eyes. Further immunostaining analysis indicates that the treatment specifically reduced the size of the abnormally large rods. These observations implicate an interesting hypothesis: that the morphologically-improved rods drive the observed VMR enhancement. Together, these investigations have identified a possible visual benefit of SchB on retinal degeneration, a benefit that can potentially be further developed to extend functional vision in patients.
Collapse
|
50
|
Viringipurampeer IA, Metcalfe AL, Bashar AE, Sivak O, Yanai A, Mohammadi Z, Moritz OL, Gregory-Evans CY, Gregory-Evans K. NLRP3 inflammasome activation drives bystander cone photoreceptor cell death in a P23H rhodopsin model of retinal degeneration. Hum Mol Genet 2016; 25:1501-16. [PMID: 27008885 DOI: 10.1093/hmg/ddw029] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 02/01/2016] [Indexed: 12/11/2022] Open
Abstract
The molecular signaling leading to cell death in hereditary neurological diseases such as retinal degeneration is incompletely understood. Previous neuroprotective studies have focused on apoptotic pathways; however, incomplete suppression of cell death with apoptosis inhibitors suggests that other mechanisms are at play. Here, we report that different signaling pathways are activated in rod and cone photoreceptors in the P23H rhodopsin mutant rat, a model representing one of the commonest forms of retinal degeneration. Up-regulation of the RIP1/RIP3/DRP1 axis and markedly improved survival with necrostatin-1 treatment highlighted necroptosis as a major cell-death pathway in degenerating rod photoreceptors. Conversely, up-regulation of NLRP3 and caspase-1, expression of mature IL-1β and IL-18 and improved cell survival with N-acetylcysteine treatment suggested that inflammasome activation and pyroptosis was the major cause of cone cell death. This was confirmed by generation of the P23H mutation on an Nlrp3-deficient background, which preserved cone viability. Furthermore, Brilliant Blue G treatment inhibited inflammasome activation, indicating that the 'bystander cell death' phenomenon was mediated through the P2RX7 cell-surface receptor. Here, we identify a new pathway in cones for bystander cell death, a phenomenon important in development and disease in many biological systems. In other retinal degeneration models different cell-death pathways are activated, which suggests that the particular pathways that are triggered are to some extent genotype-specific. This also implies that neuroprotective strategies to limit retinal degeneration need to be customized; thus, different combinations of inhibitors will be needed to target the specific pathways in any given disease.
Collapse
Affiliation(s)
- Ishaq A Viringipurampeer
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Andrew L Metcalfe
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Abu E Bashar
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Olena Sivak
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Anat Yanai
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Zeinabsadat Mohammadi
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Orson L Moritz
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Cheryl Y Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| | - Kevin Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, 2550 Willow Street, Vancouver, BC, Canada V5Z 3N9
| |
Collapse
|